Method of extracting mandrel for hollow-hat panel production

ABSTRACT

A panel may be formed with mandrels inside of stiffening members. The panel may be coupled to a panel holding jig. A winch may be coupled to the mandrels. The winch may pull the mandrels out of the stiffening members and into curved tracks.

FIELD

The present disclosure relates to an aircraft engine nacelle, and moreparticularly, to fabrication equipment and methods for compositeaircraft nacelle components.

BACKGROUND

Many components for aircraft nacelles are manufactured using compositematerials. Composite materials tend to have a high strength-to-weightadvantage compared to traditional metals. One particular application forthe use of composite materials is for fabricating panels. One type ofpanel may include a single skin with multiple laminar layers that areformed from composite materials such as graphite or an aromaticpolyamide fiber of high tensile strength that are embedded in a resinmatrix. One or more stiffening members, sometimes referred to as “hollowhats” due to their cross-sectional shape, may extend from the inside(non-aerodynamic) surface of the skin to provide additional strength tothe panel. In some cases, a mandrel is used to form the shape of thestiffening member, and the composite skin is co-cured with thestiffening member with the mandrel in place. After the curing process,the mandrel is removed from the panel. However, after the curingprocess, there may be a significant amount of friction between themandrel and the panel, and it may be difficult to remove the mandrels ina consistent manner which minimizes the possibility of damage to thecured panel or to the mandrel.

SUMMARY

A method of manufacturing a composite panel with at least one stiffeningmember formed around a removable mandrel may comprise forming a curedcomposite panel by co-curing a skin and a hollow stiffening member sothat they form a unitary structure; coupling the cured composite panelto a panel holding jig; coupling a clamp to a mandrel situated betweenthe skin of the cured composite panel and the hollow stiffening member;and operating a winch to extract the mandrel from the cured compositepanel.

In various embodiments, the method may comprise pulling the mandrel intoa curved track. The cured composite panel may be clamped to the panelholding jig. A height of the curved track may be adjusted. A pluralityof mandrels may be pulled from the cured composite panel simultaneouslyusing the winch. The winch may be operated with a hand crank. The winchmay comprise a plurality of spools.

A method of manufacturing a composite panel with at least one stiffeningmember formed around a removable mandrel may comprise curing thecomposite panel with a first mandrel inside of a stiffening member;coupling the composite panel o a panel holding jig; positioning amandrel extraction jig adjacent the panel holding jig, the mandrelextraction jig having a curved track formed thereon for receiving thefirst mandrel; and extracting the first mandrel from the stiffeningmember so that the first mandrel is supported on the curved track.

In various embodiments, the method may comprise pulling the firstmandrel into the curved track. A winch may be coupled to a secondmandrel in the composite panel. The first mandrel and the second mandrelmay be extracted simultaneously. A height of the curved track may beadjusted. The coupling the winch to the second mandrel may comprisecoupling a clamp to the second mandrel. The coupling the winch to thefirst mandrel may comprise coupling a strap to the clamp.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements.

FIG. 1 illustrates a propulsion system and its elements;

FIG. 2A illustrates a perspective view of a panel holding jig inaccordance with various embodiments;

FIG. 2B illustrates a perspective view of a mandrel in a stiffeningmember in accordance with various embodiments;

FIG. 3 illustrates a perspective view of a mandrel extraction jig inaccordance with various embodiments;

FIG. 4 illustrates a perspective view of a winch in accordance withvarious embodiments;

FIG. 5 illustrates a perspective view of a mandrel clamp in accordancewith various embodiments;

FIG. 6 illustrates a perspective view of a plurality of mandrels beingremoved from a panel in accordance with various embodiments; and

FIG. 7 illustrates a flow chart of a process for removing a mandrel inaccordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of various embodiments herein makes referenceto the accompanying drawings, which show various embodiments by way ofillustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice theinventions, it should be understood that other embodiments may berealized and that logical changes and adaptations in design andconstruction may be made in accordance with this invention and theteachings herein. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation. The scope of theinvention is defined by the appended claims. For example, the stepsrecited in any of the method or process descriptions may be executed inany order and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact.

A mandrel extraction system may comprise a panel holding jig, a mandrelextraction jig, and a winch. A rigid, cured panel may be placed in thepanel holding jig. One or more clamps may keep the cured panel secured.The cured panel is placed in an orientation so that the stiffeningmembers are horizontal. The cured panel may rest on a curved edge of thecurved panel. The winch may be attached to a mandrel still situatedinside of the stiffening member of the panel. A clamp may clamp on to anend of the mandrel, and a strap or cable coupled to the clamp may bewound around the winch using a hand crank or a winch motor. The winchmay comprise multiple straps, enabling multiple mandrels to be extractedsimultaneously. The mandrels may be pulled onto the mandrel extractionjig. The mandrel extraction jig may comprise tracks or gutters which mayguide and hold the mandrels as they are extracted from the cured panel.The tracks may be curved such that the mandrels maintain a curved shapesimilar to the shape of the panel.

Referring to FIG. 1, a nacelle 110 for a gas turbine engine isillustrated according to various embodiments. Nacelle 110 may comprisean inlet 111, a fan cowl 112, and a thrust reverser 113. Nacelle 110 maybe coupled to a pylon 114, which may mount the nacelle 110 to anaircraft wing or aircraft body.

Referring to FIG. 2A, a perspective view of a panel 210 mounted on apanel holding jig 220 is illustrated according to various embodiments.In various embodiments, the panel 210 may be a fan cowl panel, and thepanel holding jig 220 may be a fan cowl holding jig. The panel holdingjig 220 may comprise a base 222 and a plurality of vertical posts 224.The base 222 ay be curved to accommodate the shape of the panel 210. Thevertical posts 224 may be adjustable on tracks 225 to accommodatedifferent shapes of panels. The panel holding jig 220 may comprise aplurality of clamps 226. The clamps 226 may be coupled to the verticalposts 224. The clamps 226 may be configured to clamp to the panel 210 tokeep the panel 210 in place. The clamps 226 may be vertically adjustablealong the vertical posts 224. Additionally, the clamps may be rotated tothe interior of the panel holding jig 220 to hold smaller panels.

The panel 210 may comprise a curved panel with stiffening members 212.The panel 210 may be oriented such that the stiffening members 212 areoriented horizontally (e.g. parallel to the ground). The stiffeningmembers 212 may be formed from a composite skin around mandrels 214. Thestiffening members 212 may be cured with the mandrels 214 located withinthe stiffening members 212. The mandrels 214 may comprise an elongatedrubber or other elastomeric component which is configured to be removedfrom the stiffening members 212 after curing of the panel 210. A portionof the mandrels 214 may extend outside the ends of the stiffeningmembers 212 to allow the mandrels 214 to be accessed for removal. Thehorizontal orientation of the stiffening members 212 may allow themandrels 214 to be more easily removed. The stiffening members 212 maybe referred to as a “hollow hat.”

Referring to FIG. 2B, a perspective view of a mandrel 52 in a hollowstiffening member 16 is illustrated according to various embodiments.The skin 12 of a panel may comprise a first layer 34 and a second layer38. The first layer 34 and the second layer 38 may each comprise one ormore composite layers formed from a fabric bonded together by a resinmatrix. The panel may comprise a stiffening member 16. The stiffeningmember 16 may be formed by placing a mandrel 52 between the first layer34 and the second layer 38. The first layer 34 and the second layer 38may be co-cured with the mandrel 52 in place in order to form thestiffening member 16. The stiffening member 16 may take the shape of themandrel 52, which may comprise flat sides 54 and angled sides 36. Theskin 12 may be cured on a lay-up mandrel 32 to provide the general shapeof the skin 12. The first layer 34 and the second layer 38 may bestructurally bonded together into a unitary structure during the curingprocess.

Referring to FIG. 3, a perspective view of a mandrel extraction jig 320coupled to the panel holding jig 220 is illustrated according to variousembodiments. The mandrel extraction jig 320 may comprise a curved base322. A plurality of vertical posts 324 may be coupled to the curved base322. A plurality of horizontal curved tracks 326 may be coupled to thevertical posts 324. The curved tracks 326 may be configured to supportthe mandrels as the mandrels are removed from the panel 210. Thevertical posts 324 may comprise a mounting track 325. The curved tracks326 may be coupled to different heights on the mounting track 325 tocorrespond to the heights of the stiffening members on the panel 210. Anadjustable support 327 may be coupled to the curved base 322. Theadjustable support 327 may be raised or lowered to adjust the height ofthe curved tracks 326. A winch 330 may be coupled to the curved base322. The winch 330 may comprise a plurality of spools 332. The winch 330may be operated by a hand crank 334 or by a motor 336.

Referring to FIG. 4, a perspective view of the winch 330 is illustratedaccording to various embodiments. The hand crank 334 may be turned inorder to wind-up or pay-out straps 335 on the spools 332. The winch 330may operate multiple spools 332 simultaneously in order to removemultiple mandrels simultaneously.

Referring to FIG. 5, a perspective view of a mandrel clamp 510 isillustrated according to various embodiments. The mandrel clamp 510 maybe coupled to a mandrel 214. The mandrel clamp 510 may comprise anattachment ring 512. A clip 514 may be coupled to the attachment ring512. The clip 514 may be coupled to a strap or cable, which may beoperated by the winch. When the winch is operated, the winch may pullthe mandrel 214 out of the stiffening member 212.

Referring to FIG. 6, a perspective view of two mandrels 214 beingremoved is illustrated according to various embodiments. The straps 335may pull the mandrel clamps 510 which are coupled to the mandrels 214.The mandrels 214 may be pulled into the curved tracks 326. The mandrels214 may remain in a curved shape in the curved tracks 326 to preventdeformation of the mandrels 214.

Referring to FIG. 7, a flowchart of a process 700 for removing mandrelsis illustrated according to various embodiments. A panel may be coupledto a holding jig (step 710). In various embodiments, the panel may beclamped to the holding jig. The panel may be oriented such that thestiffening members are horizontal, i.e. parallel to the ground. Tracksin a mandrel extraction jig may be adjusted to correspond to the heightof the mandrels (step 720). A mandrel clamp may be coupled to a mandrelin a stiffening member in the panel (step 730). In various embodiments,a mandrel clamp may be coupled to each mandrel in the panel. A winch aybe operated to pull the mandrels out of the stiffening members (step740). The mandrels may be pulled into the tracks in the mandrelextraction jig. The clamps may be detached from the mandrels, and themandrels may be removed from the mandrel extraction jig (step 750). Thepanel may be removed, and additional panels may be coupled to theholding jig to remove mandrels.

Although described primarily with reference to fan cowl panels, thoseskilled in the art will recognize that the systems and method describedherein may be used to remove mandrels from many different components invarious industries.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f), unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

We claim:
 1. A method of manufacturing a composite panel with at leastone stiffening member formed around a removable mandrel comprising:forming a cured composite panel by co-curing a skin and a hollowstiffening member so that they form a unitary structure; coupling thecured composite panel to a panel holding jig; coupling a clamp to amandrel situated between the skin of the cured composite panel and thehollow stiffening member; and operating a winch to extract the mandrelfrom the cured composite panel.
 2. The method of claim 1, furthercomprising pulling the mandrel into a curved track.
 3. The method ofclaim 1, further comprising clamping the cured composite panel to thepanel holding jig.
 4. The method of claim 2, further comprisingadjusting a height of the curved track.
 5. The method of claim 1,further comprising pulling a plurality of mandrels from the curedcomposite panel simultaneously using the winch.
 6. The method of claim1, further comprising operating the winch Id crank.
 7. The method ofclaim 1, wherein the winch comprises a plurality of spools.
 8. A methodof manufacturing a composite panel with at least one stiffening memberformed around a removable mandrel comprising: curing the composite panelwith a first mandrel inside of a stiffening member; coupling thecomposite panel to a panel holding jig; positioning a mandrel extractionjig adjacent the panel holding jig, the mandrel extraction jig having acurved track formed thereon for receiving the first mandrel; andextracting the first mandrel from the stiffening member so that thefirst mandrel is supported on the curved track.
 9. The method of claim8, further comprising pulling the first mandrel into the curved track.10. The method of claim 8, further comprising coupling a winch to asecond mandrel in the composite panel.
 11. The method of claim 10,further comprising extracting the first mandrel and the second mandrelsimultaneously.
 12. The method of claim 9, further comprising adjustinga height of the curved track.
 13. The method of claim 10, wherein thecoupling the winch to the second mandrel comprises coupling a clamp tothe second mandrel.
 14. The method of claim 13, wherein the coupling thewinch to the first mandrel comprises coupling a strap to the clamp.